JP2013235680A - Current collector for storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage battery having a smaller internal resistance and a longer charge-discharge cycle life, and less prone to suffer deterioration owing to rapid charge and discharge by forming an electrode improved in adhesion between a current collector and an electrode material.SOLUTION: The current collector for a storage battery is a current collector formed by using a conductive electrically-deposited coating material including a cation-based resin or an anion-based resin, a conducting agent and water and if necessary, an additive agent such as a solvent or surfactant to form, by electrodeposition, a conductive coating film on at least one surface of the current collector.

Description

  The present invention relates to a current collector of a secondary battery such as a lithium ion battery and a storage battery such as a capacitor such as an electric double layer capacitor or a lithium ion capacitor, and the adhesion between the current collector and the electrode material is improved. The present invention relates to a current collector material that can provide a storage battery with low internal resistance, little deterioration during rapid charge / discharge, and a long charge / discharge cycle life.

Lithium ion batteries have high energy density and high voltage, and are therefore used in electronic devices such as mobile phones, notebook computers, and camcorders. Recently, the application as a storage battery for in-vehicle use such as an electric vehicle and a hybrid electric vehicle and for storage of electric power for home use is also progressing.
The electric double layer capacitor has a relatively large capacity and can be charged and discharged for a long time and can be used for replenishing or replacing the power source for starting the cell motor, the memory backup power source of the personal computer, and the secondary battery. It is considered to be applied to automobiles.
Lithium ion capacitors can increase the energy density while maintaining rapid charge / discharge performance by increasing the potential difference between the positive and negative electrodes by pre-doping lithium ions. Adoption has begun.

  A lithium ion battery is generally composed of a positive electrode, a negative electrode, a separator, an electrolytic solution, and a current collector. The positive electrode is composed of a layered positive electrode active material such as lithium cobaltate or spinel type lithium manganate and a conductive additive such as carbon black, a binder such as polyvinylidene fluoride or polytetrafluoroethylene, and N-methylpyrrolidone A coating liquid dispersed in such a polar solvent is applied on a current collector foil typified by an aluminum foil and dried. The negative electrode has a negative electrode active material such as graphite or hard carbon capable of inserting and desorbing lithium ions, and a coating liquid consisting of a conductive additive, a binder, and a solvent on a copper foil as a current collector in the same manner as the positive electrode. Obtained by coating and drying. As the separator, polyethylene or polypropylene subjected to a porous treatment or a non-woven fabric is used. As the electrolytic solution, an electrolyte such as lithium hexafluorophosphate dissolved in a cyclic carbonate such as ethylene carbonate or a linear ether such as diethyl ether is used.

  The electric double layer capacitor is composed of a positive electrode, a negative electrode, a separator, an electrolytic solution, and a current collector, like a lithium ion battery. A coating solution made of activated carbon having a large specific surface area, a conductive additive, a binder, and a solvent is applied onto an aluminum foil and dried, and then used as a positive electrode and a negative electrode. An electrolytic solution in which a quaternary onium salt such as tetraethylammonium tetrafluoroborate is dissolved in an organic solvent is employed.

  The structure of a lithium ion capacitor is similar to that of an electric double layer capacitor, but a conductive polymer such as graphite or polyacene is used for the negative electrode active material, and lithium ions are pre-doped from a metal lithium foil attached on the negative electrode. The copper foil as the negative electrode current collector has a perforated structure that allows lithium ions to pass therethrough.

  The problem with these storage batteries is that due to insufficient adhesion between the positive and negative electrodes and the current collector, the internal resistance and storage capacity of the storage battery increase over time based on the resistance between the electrode and current collector interface. Is what happens. This is particularly noticeable in lithium ion batteries where the volume change rate of the positive electrode material and the negative electrode material is large due to charging / discharging. The use is a common problem for storage batteries.

  In order to maximize the energy stored in storage batteries and to increase productivity and reduce manufacturing costs, a positive and negative electrode composition with as much positive and negative electrode active material as possible is applied to the current collector in a thick film at once. The process of drying is adopted. For this reason, if there are not enough conductive assistants and binders, poor adhesion due to repeated charging / discharging and the influence of the usage environment will increase the resistance at the interface with the current collector, increasing contact resistance and electron conduction path It is considered that the battery performance is deteriorated due to lack of. In addition, an oxide film generated on the surface of the current collector is also considered as one factor of poor adhesion. Pretreatment of the current collector surface by immersion in an alkaline solution such as sodium hydroxide or ethanolamine or an acid solution such as hydrochloric acid is an effective means, but the film is re-formed in a relatively short time after the treatment is completed. Therefore, there is a drawback that the treated current collector cannot be stored. If the amount of the positive and negative electrode active materials is reduced and the amount of the binder and the electron conductive material is increased, this problem can be solved, but the energy density is reduced and the function as a storage battery is lowered.

  In order to solve the above problems, Patent Documents 1 to 3 apply a coating solution in which conductive carbon is mixed and dispersed in a polysaccharide polymer such as chitin and chitosan or a hydroxyalkyl derivative thereof as a binder. It has been proposed to do. However, in the die coater method or the casting method, it is difficult to control the conductive film to a thin film having a uniform thickness, and there remains a problem that the electron transfer between the electrode and the current collector is not uniform. Furthermore, it is difficult to apply the coating inside a current collector made of a perforated foil, a foam metal having a three-dimensional structure, or a sintered metal.

JP 2009-277660 A JP2012-23050 WO2008 / 015828

  The present invention has been made in view of the above circumstances, and provides a storage battery having improved charge / discharge cycle life, improved adhesion between a current collector and an electrode material, low internal resistance, little deterioration during rapid charge / discharge. For the purpose.

As a result of repeated studies to achieve the above object, the present inventors have found that the above-mentioned problems can be solved by forming a conductive film on the surface of the battery current collector by an electrodeposition coating method. It came to. That is, the present invention relates to the following.
(1) A current collector for a storage battery, wherein a conductive film is formed on a current collector substrate by an electrodeposition coating method.
(2) The current collector for a storage battery according to (1), wherein a conductive electrodeposition paint containing a cationic polymer resin or an anionic polymer resin and a carbon particle conductive agent is used.
(3) The current collector for a storage battery according to (1) or (2), wherein the current collector base is made of a metal or an alloy, and the thickness of the conductive coating is 0.1 to 15 μm.
(4) The current collector for a storage battery according to (2) or (3), wherein the carbon particle conductive agent has a diameter of 3 μm or less.
(5) The current collector for a storage battery according to any one of (1) to (4), wherein the current collector base is made of a perforated metal foil or a foam metal.
(6) The manufacturing method of the electrical power collector for storage batteries in any one of (1)-(5).
(7) A storage battery using a storage battery electrode and a storage battery electrode produced by applying a coating liquid containing an electrode active material to the storage battery current collector according to any one of (1) to (5).

  The storage battery using the current collector according to the present invention has excellent adhesion between the electrode and the current collector, and has a low resistance. Therefore, the capacity retention rate is high even under rapid charge / discharge, and the internal resistance is low. It is suitable for a storage battery having a long life and excellent high input / output characteristics.

It is a schematic block diagram of the electrodeposition coating process shown to embodiment.

  Hereinafter, the present invention will be described in more detail. The current collector for a storage battery according to the present invention is characterized in that a conductive film is formed on a current collector substrate by an electrodeposition coating method. The conductive film in the present invention is a film obtained by electrically attaching a conductive agent (including resin and various additives) having electrical conductivity to the surface of the current collector substrate. It is a film covered with a uniform thickness.

(1) Electrodeposition coating method The electrodeposition coating method is a means for forming a resin film having a positive or negative charge on an electrically conductive object to be coated. This is a coating method that can be easily obtained with a uniform film thickness by controlling the current or voltage because the coating equipment becomes unnecessary and is inexpensive. In addition, all parts can be coated with a uniform thickness even on complicated shapes with holes and three-dimensional structures that are impossible with the usual doctor blade method, dip method, transfer method, and printing. It has the characteristics. That is, the end surface of the hole of the perforated current collector foil used as the current collector of the lithium ion capacitor and the surface of the sintered metal or foamed resin to which the powder that is the current collector of the alkaline liquid secondary battery is fixed are covered with nickel or the like. In addition, a conductive film can be formed with a uniform film thickness inside the foamed current collector. The conductive film in the present invention is obtained by anionic electrodeposition coating or cationic electrodeposition coating.

(2) Electrodeposition paints Electrodeposition paints for electrodeposition coating used in the present invention are roughly classified into cationic electrodeposition paints and anion electrodeposition paints depending on whether the charge to be charged is positive or negative. The polymer resin used in the electrodeposition paint is used in a form neutralized with a neutralizing agent, and diluted in an aqueous medium together with a conductive agent and, if necessary, additives such as a cross-linking agent, a solvent and a surfactant. Dispersed and becomes a positively or negatively charged paint component. Depending on the shape and size of these resins present in water, a water-soluble type, a colloid type, a dispersion type, or an emulsion type may be used. Moreover, what is necessary is just the thing which is electrochemically stable, does not elute to electrolyte solution, and the swelling by electrolyte solution is small.

As the polymer resin for the cationic electrodeposition coating, for example, a resin having a functional group such as an amino group, an ammonium base, a sulfonium base, or a phosphonium base and capable of being cationized in an aqueous medium can be used. Examples of such resins include onium-type acrylic resins, epoxy resins, polyamide resins, polyester resins, polybutadiene resins, alkyd resins, and the like, which are cationic polymer resins having a molecular weight of about 1,000 to 50,000. These are generally used, and these are used alone or in combination of two or more. Further, an amine such as dimethylethanol may be reacted with the resin and introduced into the resin structure. In order to increase the strength of the coating or to reduce the solubility and swelling in the electrolyte, it can be used in combination with a crosslinkable polymer resin such as polyurethane resin or a crosslinking agent capable of introducing a crosslinked structure such as an isocyanate group. These resins are used in a form neutralized with a neutralizing agent that is an acidic substance such as acetic acid, glacial acetic acid, formic acid, lactic acid, and propionic acid.
Examples of the resin in which an amine is introduced into the epoxy resin include an amine epoxy adduct obtained by reacting bisphenol A diglycidyl ether with dimethylethanolamine.

  As the polymer resin of the anion electrodeposition coating, a resin having a functional group such as a carboxyl group in the resin and capable of anionization in an aqueous medium can be used. Examples of such resins include acrylic resin systems, polyester resin systems, maleated oil resin systems, epoxy resin systems, polybutadiene resin systems, and the like, which are anionic polymer resins having a molecular weight of about 300 to 30,000. Or two or more types are used in combination. Further, in order to increase the strength of the film or to reduce the solubility and swelling property with respect to the electrolytic solution, it can be used in combination with a crosslinkable polymer resin such as a phenol resin, diallyl phthalate resin, or melamine resin. These resins are used after being neutralized with a neutralizing agent which is an alkaline substance such as amines such as potassium hydroxide, triethylamine, diethylamine, dimethylmethanolamine, diisopanolamine, or ammonia.

As the conductive agent that can be used in the present invention, carbon particles such as graphite, hard carbon, acetylene black, ketjen black, vapor grown carbon fiber, carbon nanotube, and carbon nanohorn are suitable, but there is no particular limitation. Can be used in combination. As the shape of the conductive agent, those having anisotropy such as needles or rods are more desirable than spherical ones having high electron conductivity, a large contact area, and a large specific surface area.
The size in the length direction of the conductive agent having such anisotropy is preferably smaller than the film thickness of the conductive coating, and the carbon particles have a diameter of 5 μm or less, preferably 3 μm or less, more preferably 1 μm or less. Is desirable.

  Examples of the crosslinking agent that can be used in the present invention include crosslinkable resins such as melamine, isocyanate, polyester resin, melamine resin, phenol resin, urethane resin, and diallyl phthalate resin. Preferred examples of the crosslinking agent include melamine, isocyanate, polyester resin, and melamine resin. As a catalyst for inducing crosslinking, a tin compound such as dibutyltin laurate may be added and heated. In order to promote crosslinking, it is effective to reduce the viscosity of the crosslinking agent. In that case, a solvent such as 2-ethylhexanol may be added.

  The main solvent of the electrodeposition paint is water, but pure water and deionized water are preferred. Further, a solvent may be used for improving the uniform electrodeposition. The solvent is not particularly limited, but it is preferable to use a solvent that is soluble in water. Examples of such solvents include lower alcohols such as ethyl alcohol and isopropyl alcohol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, and diethylene glycol monoethyl ether. And glycol ether solvents such as ethylene glycol monobutyl ether, propylene glycol monophenyl ether, ethylene glycol mono (2-ethylhexyl) ether, and ethylene glycol monohexyl ether, benzyl alcohol, methyl ethyl ketone, and methyl isobutyl ketone. These can be used alone or in combination of two or more. Among these, propylene glycol monomethyl ether, ethylene glycol monobutyl ether, methyl ethyl ketone, methyl isobutyl ketone and the like are preferable.

  Examples of the surfactant used in the present invention include sorbitan fatty acid ester, polyoxyethylene fatty acid ester, alkyl sulfate ester salt, polyoxyethylene alcohol ether and the like.

As a method for producing the electrodeposition paint used in the present invention, it may be dissolved or dispersed in water together with a resin, a conductive agent and, if necessary, a crosslinking agent, a solvent, an additive and the like. As a method for dissolving or dispersing the composition comprising these components, a resin, a conductive agent, and a cross-linking agent as needed, using a normal stirrer, disperser, kneader, planetary ball mill, three-roll, homogenizer, etc. After mixing, the mixture can be efficiently mixed by diluting with ion exchange water or pure water. Further, in order to increase the efficiency of dissolution or dispersion, heating may be performed within a range that does not affect the material.

(3) Current collector substrate The current collector substrate that can be used in the present invention is not particularly limited, but is required to be conductive and inert to the electrochemical reaction in the storage battery. , Metals such as aluminum, copper, nickel, iron, chromium, and alloys thereof. In the case of a lithium ion battery or lithium ion capacitor, the positive electrode is generally aluminum, the negative electrode is copper, and in the case of an electric double layer capacitor, aluminum is generally used for both the positive and negative electrodes. As the copper foil for the lithium ion capacitor, a metal foil having a perforated structure that allows lithium ions to pass therethrough is used in order to pre-dope lithium ions from a metal lithium foil attached on the negative electrode. Therefore, preferable current collector bases include aluminum foil and copper foil. The copper foil is preferably a rolled copper foil or an electrolytic copper foil.

  As the shape of the current collector base, the metal or alloy foil, the surface of which is roughened by a chemical or electrochemical technique, and a hole having a diameter of 50 to 500 μm as a perforated metal foil Porous sintered metal obtained by sintering and solidifying perforated foil and metal particles, nickel, copper, and tin coatings are formed on the urethane foam surface by electroless plating and electrolytic plating, and then heated in a reducing atmosphere. Examples of the metal foam obtained are also examples. The thickness of the foam sheet made of the foam metal is 100 μm to 2 mm, preferably 100 μm to 1 mm.

  The thickness of the current collector substrate is preferably 5 μm to 100 μm. If the thickness is less than 5 μm, the foil may break in the electrodeposition coating process due to insufficient strength. If the thickness exceeds 100 μm, the volume and weight of the current collector base in the storage battery increase, and the volume and weight per unit This is not preferable because the capacity of the storage battery is reduced.

  The current collector substrate is preferably degreased with an alkaline solution such as 5% aqueous sodium hydroxide or ethanolamine or an acid solution such as hydrochloric acid before electrodeposition coating to remove the surface coating. In particular, it is necessary when the conductive film is formed uniformly and with good adhesion to the inner surface of the perforated metal foil having pores in the thickness direction and three-dimensional direction.

(4) Method for producing current collector for storage battery As a method for forming a conductive film on the surface of the current collector substrate by the electrodeposition coating method according to the present invention, electrodeposition in the case where a continuous foil is used as the current collector substrate in FIG. The painting method will be described. The current collector base 2 having conductivity is sent to the feeding roll 3 by the unwinding roll 1 and is given a positive or negative charge. The current collector base 2 is guided to an electrodeposition coating tank 4 filled with an electrodeposition paint 5, and is applied with a direct current to cause an electrophoretic action between the counter electrode 6 having a charge opposite to that of the current collector base 2. Resin and filler in the paint are deposited on the current collector surface. The counter electrode is preferably separated from the electrodeposition paint by a neutral diaphragm or an ion exchange membrane, but may not be separated. In the case of cationic electrodeposition coating, the current collector substrate is a negative electrode and the counter electrode is a positive electrode. The reverse is true for anionic electrodeposition coating. Thereafter, the film is wound around a winding roll 10 through a recovery tank 7, a washing tank 8, and a drying tank 9. The electrodeposition paint collected in the collection tank 7 is sent to the electrodeposition paint receiving tank 11 via the electrodeposition paint collection line 12, and after the concentration is adjusted, the electrodeposition paint tank 4 is supplied from the pump 13 and the electrodeposition paint supply line 14. Returned to

In general, a film is obtained under the conditions that the liquid temperature of the electrodeposition paint is 10 to 40 ° C., the applied voltage is 10 to 200 V, and the current is 0.5 to 30 A / dm ² .
The thickness of the conductive coating is preferably from 0.1 to 15 μm, particularly preferably from 0.2 to 10 μm. If the film thickness is less than 0.1 μm, the adhesion between the current collector and the electrode material is not sufficient, and if it exceeds 15 μm, the energy density of the storage battery decreases, which is not preferable.

(5) Manufacturing method of electrode The manufacturing method of the electrode using the electrical power collector for storage batteries provided with the electroconductive film layer of this invention is not specifically limited, A general method is used. In the case of an electrode for a lithium ion battery, a paste (coating liquid) composed of a positive electrode active material or a negative electrode active material, a conductive additive, a binder, a solvent, etc. is applied onto the current collector surface by a doctor blade method or a silk screen method. It is performed by uniformly applying to an appropriate thickness. After the application, the electrode is dried by, for example, hot air at 100 ° C. or vacuum at 80 ° C. in order to remove excess solvent. The electrode after drying is press-molded by a press device as necessary to produce an electrode.

Such a positive electrode active material is an alkali metal-containing composite oxide powder having a composition of any one of AMO ₂ , AM ₂ O ₄ , A ₂ MO ₃ , and AMXO ₄ . Here, A in the formula is an alkali metal, and Li is preferably used. M is mainly composed of a transition metal and contains at least one of Co, Mn, Ni, Cr, Fe, and Ti. M is made of a transition metal, but Al, Ga, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc. may be added in addition to the transition metal. X contains at least one of P and Si. The particle diameter of the positive electrode active material is 50 μm or less, preferably 20 μm or less. These active materials have an electromotive force of 3 V (vs. Li / Li +) or more.

Specific examples of the positive electrode active material include lithium cobaltate, lithium nickelate, nickel / manganese / lithium cobaltate (ternary system) for AMO ₂ type, spinel type lithium manganate for AM ₂ O ₄ type, and AMBO ₄ type. Examples thereof include lithium iron phosphate.

  As the negative electrode active material, a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.) having a structure (porous structure) capable of occluding and releasing alkali metal ions such as lithium ions, or alkali metal ions such as lithium ions Is a powder made of metal such as lithium, aluminum compound, tin compound, silicon compound, titanium compound, etc. The particle diameter is preferably from 10 nm to 100 μm, more preferably from 20 nm to 20 μm. Moreover, you may use as a mixed active material of a metal and a carbon material.

  Specific examples of the conductive auxiliary agent include conductive carbon black such as graphite, furnace black, acetylene black, and ketjen black, or metal powder, but are not limited thereto.

  As the binder, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, polyether, or styrene butadiene rubber can be used, but not limited thereto.

  In the case of an electrode for an electric double layer capacitor, the same as in the case of a lithium ion battery, but the allotrope of carbon is used for both the positive electrode active material and the negative electrode active material, and the electrode active material used in the electric double layer capacitor can be widely used. .

  Specific examples of the allotrope of carbon include activated carbon, polyacene (PAS), carbon whisker, and graphite, and these powders or fibers can be used. Among these, activated carbon is preferable. Specific examples of the activated carbon include activated carbon made from phenol resin, rayon, acrylonitrile resin, pitch, coconut shell, and the like. When carbon allotropes are used in combination, two or more carbon allotropes having different average particle diameters or particle size distributions may be used in combination. Moreover, as an electrode active material used for the positive electrode, in addition to the above materials, a polyacene-based skeleton structure which is a heat-treated product of an aromatic condensation polymer and has an atomic ratio of hydrogen atom / carbon atom of 0.50 to 0.05 A polyacene-based organic semiconductor (PAS) having the following can also be suitably used.

  The electrode for a lithium ion capacitor is similar to an electric double layer capacitor, but a conductive polymer such as graphite or polyacene is used for the negative electrode active material.

  Any solvent may be used as long as it can uniformly disperse the positive electrode active material or the negative electrode active material, the conductive additive, and the binder. For example, N-methyl-2-pyrrolidone or water can be used.

(6) Manufacturing method of storage battery The manufacturing method of the storage battery using the electrode of this invention is not specifically limited, It is comprised with a positive electrode, a negative electrode, a separator, electrolyte solution, and an electrical power collector, and is manufactured by a well-known method. For example, in the case of a cylindrical can storage battery, the positive electrode, the separator, the negative electrode, and the second separator are wound in a coil shape and inserted into the outer can. This is impregnated with an electrolytic solution. Then, it joins with a sealing body by tab welding etc., a sealing body is enclosed, and a storage battery is obtained by crimping.

  As the separator, a positive electrode and a negative electrode are directly contacted to prevent short-circuiting in the storage battery, and a known material can be used. Specifically, it is made of a porous polymer film such as polyolefin or paper. As the porous polymer film, a film such as polyethylene or polypropylene is preferable because it is not affected by the electrolytic solution.

The electrolytic solution is a mixture composed of an electrolyte salt compound and an aprotic organic solvent. As electrolyte salt compounds, cations selected from metal cations, ammonium ions, amidinium ions, and guanidinium ions, as well as chlorine ions, bromine ions, iodine ions, perchlorate ions, thiocyanate ions, tetrafluoroboron ions. Acid ion, nitrate ion, AsF ₆ ⁻ , PF ₆ ⁻ , stearyl sulfonate ion, octyl sulfonate ion, dodecylbenzene sulfonate ion, naphthalene sulfonate ion, dodecyl naphthalene sulfonate ion, 7,7,8,8-tetracyano -p- quinodimethane ^{_{ion, X 1 SO 3 -, [}} (X 1 SO 2) (X 2 SO 2) N] -, [(X 1 SO 2) (X 2 SO 2) (X 3 SO 2) C] ^-, and _{[(X 1 SO 2) (} X 2 SO 2) YC] - compounds comprising the selected anions from are mentioned . _{However, X 1, X 2, X} 3, and Y is an electron withdrawing group. Preferably, X ₁ , X ₂ and X ₃ are each independently a C 1-6 perfluoroalkyl group or a C 6-18 perfluoroaryl group, Y is a nitro group, a nitroso group, A carbonyl group, a carboxyl group or a cyano group; X ₁ , X ₂ and X ₃ may be the same or different.

  As the metal cation, a cation of a transition metal can be used. Preferably, a metal cation selected from Mn, Fe, Co, Ni, Cu, Zn, and Ag metal is used. In addition, preferable results can be obtained by using a metal cation selected from Li, Na, K, Rb, Cs, Mg, Ca, and Ba metals. It is free to use two or more kinds of the aforementioned compounds in combination as the electrolyte salt compound. In the lithium ion battery, a lithium salt compound is preferably used as the electrolyte salt compound.

As the lithium salt compound, a lithium salt compound having a wide potential window, which is generally used for lithium ion batteries and lithium ion capacitors, is used. For example, LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN [CF ₃ SC (C ₂ F ₅ SO ₂ ) ₃ ] _{2 and the} like, but are not limited thereto. These may be used alone or in combination of two or more.

  Examples of aprotic organic solvents include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane. Straight chain ethers such as dipropyl carbonate, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propyl nitrile, anisole, acetate ester, propionate ester, diethyl ether can be used. Also good.

  Moreover, a normal temperature molten salt can be used as an electrolyte salt compound or an electrolyte solution. The room temperature molten salt refers to a salt that is at least partially in a liquid state at room temperature, and the room temperature refers to a temperature range in which a power supply is assumed to normally operate. The temperature range in which the power supply is assumed to normally operate has an upper limit of about 120 ° C. and in some cases about 60 ° C., and a lower limit of about −40 ° C. and in some cases about −20 ° C.

  The room temperature molten salt is also called an ionic liquid, and pyridine, aliphatic amine and alicyclic amine quaternary ammonium organic cations are known. Examples of the quaternary ammonium organic cation include imidazolium ions such as dialkylimidazolium and trialkylimidazolium, tetraalkylammonium ions, alkylpyridinium ions, pyrazolium ions, pyrrolidinium ions, and piperidinium ions. In particular, an imidazolium cation is preferable.

  Examples of tetraalkylammonium ions include, but are not limited to, trimethylethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, tetrapentylammonium ion, and triethylmethylammonium ion. is not.

  Examples of the alkylpyridium ion include N-methylpyridinium ion, N-ethylpyridinium ion, N-propylpyridinium ion, N-butylpyridinium ion, 1-ethyl-2-methylpyridinium ion, 1-butyl-4-methylpyridinium ion Ions, 1-butyl-2,4 dimethylpyridinium ions and the like, but are not limited thereto.

  Examples of the imidazolium cation include 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, 1-methyl-3-ethylimidazolium ion, 1-methyl-3-butylimidazolium ion, 1- Butyl-3-methylimidazolium ion, 1,2,3-trimethylimidazolium ion, 1,2-dimethyl-3-ethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl- Examples include 2,3-dimethylimidazolium ion, but are not limited thereto.

  In addition, the normal temperature molten salt which has these cations may be used independently, or may mix and use 2 or more types.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to the following Example.

[Preparation example of electrodeposition paint]
Example of preparation of cationic electrodeposition paint 50 parts by weight of ethylene glycol monoethyl ether was dissolved in 100 parts by weight of bisphenol A diglycidyl ether (epoxy equivalent 800) at a liquid temperature of 80 ° C., heated to 100 ° C. and then dimethylethanolamine Was added and reacted for 3 hours to prepare an amine epoxy adduct (A).
Further, 0.005 parts by weight of dibutyltin laurate is added to 100 parts by weight of an isocyanate-based cross-linking agent having a nonvolatile content of 75% by weight (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.), and 40 parts by weight of 2-ethylhexanol is further added to 130 parts. A reaction product (B) reacted at 3 ° C. for 3 hours was obtained.
After adding 5 parts by weight of ethylene glycol monobutyl ether to a mixture consisting of 100 parts by weight of the above-mentioned amine epoxy adduct (A) and 35 parts by weight of the reaction product (B), the mixture is neutralized with 3 parts by weight of glacial acetic acid and ion exchanged. It was diluted with 50 parts by weight of water to prepare an electrodeposition solution having a nonvolatile content of 50% by weight.
Planetary type by adding 20 parts by weight of Ketjen Black manufactured by Lion Corporation having an average primary particle diameter of 35 nm and 5 parts by weight of carbon nanotubes manufactured by Showa Denko Co., Ltd. to 100 parts by weight of the electrodeposition liquid. After being dispersed for 24 hours by a ball mill, it was diluted with ion-exchanged water to obtain a cationic electrodeposition paint having a nonvolatile content of 25% by weight.

Example of preparation of anion electrodeposition coating material 100 parts by weight of polyester resin (manufactured by Shinto Paint Co., Ltd.) having a nonvolatile content of 75%, 25 parts by weight of melamine resin (manufactured by Mitsui Cyanamid Co., Ltd.), 8 parts by weight of dimethylmethanolamine and ion exchange 80 parts by weight of water was mixed and dispersed with a homogenizer for 1 hour to prepare an electrodeposition solution having a nonvolatile content of 50% by weight.
After kneading and dispersing 3 parts by weight of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.) having an average particle size of 35 nm and 3 parts by weight of carbon nanotubes by Showa Denko Co., Ltd. with three rolls with respect to 100 parts by weight of the electrodeposition liquid. The anion electrodeposition paint having a nonvolatile content of 20% by weight was obtained by dilution with ion exchange water.

[Preparation example of current collector with conductive film]
Current collector preparation example 1
Toyo Aluminum with a thickness of 50 μm, a width of 300 mm, and a length of 200 m obtained by removing the surface coating from the cationic electrodeposition paint obtained in the preparation example of the cationic electrodeposition paint at a liquid temperature of 25 ° C. Aluminum foil (A1085 material) current collector base made by Co., Ltd. was immersed and connected to the cathode, electrodeposition was applied under a current of 1 minute at a voltage of 40 V, followed by washing with spray and drying at 130 ° C. Thereafter, a current collector with a conductive film having a thickness of 5 μm was obtained.

Current collector preparation example 2
Conductive film having a conductive film thickness of 5 μm was prepared in the same manner as in current collector preparation example 1 except that the electrodeposition paint was an anion electrodeposition paint obtained in the anion electrodeposition paint preparation example and aluminum was connected to the anode. A current collector with a film was obtained.

Current collector preparation example 3
Instead of the aluminum foil, a copper foil with a thickness of 12 μm, a width of 300 mm, and a length of 200 m made by Nippon Foil Co., Ltd. was used, and the same means as in the current collector adjustment example 1 except that the energization time was 30 seconds. A current collector with a conductive film having a thickness of 2 μm was obtained.

Current collector preparation example 4
The conductive film was formed in the same manner as in Preparation Example 2 of the current collector, except that the aluminum foil current collector substrate used in Preparation Example 1 was made into a perforated aluminum foil having an average pore diameter of 100 μm and an aperture ratio of 50% by photolithography. A perforated current collector with a conductive film having a thickness of 5 μm was obtained.

Current collector preparation example 5
A nickel conductive layer is formed by electroless plating on a 300 mm wide foamed urethane sheet having continuous holes with a three-dimensional structure, which is used as a current collector material for positive electrodes of nickel metal hydride batteries, and then a copper layer is formed by electrolytic copper sulfate plating I let you. This sheet was fired in an oxidizing atmosphere at 600 ° C. for 1 hour to decompose urethane, and then heat-treated at 1,000 ° C. for 30 minutes in a reducing atmosphere of ammonia decomposition gas to obtain a foamed copper sheet. The thickness of the sheet was 0.8 mm, the average pore diameter was 70 μm, and the basis weight of copper was 250 g / m ² . This sheet was immersed in the cationic electrodeposition coating material obtained in the preparation example of the cationic electrodeposition coating material and connected to the cathode, and electrodeposition coating was performed at a voltage of 40 V and an energization time of 40 seconds. After drying, a current collector with a conductive film having a conductive film thickness of 3 μm was obtained.

[Example of electrode / current collector production]
Preparation Example of Positive Electrode / Current Collector The positive electrode material paste uses lithium cobaltate as an active material, acetylene black as a conductive auxiliary agent, polyvinylidene fluoride as a binder, and N-methyl- Obtained by mixing and dispersing in 2-pyrrolidone solvent. The ratio of each component was positive electrode active material: conducting aid: binder: solvent = 85: 2: 3: 10 (weight ratio). This paste was applied to the current collector obtained in the current collector preparation example with a die coater, dried at 130 ° C. for 3 hours, and then pressed with a roll press to obtain a positive electrode / current collector.
Preparation Example of Negative Electrode / Current Collector The negative electrode material paste was prepared by using natural graphite as an active material, and was prepared by the same composition and formulation as the above positive electrode paste. Like the positive electrode, the paste was applied to each current collector with a die coater, dried at 130 ° C. for 3 hours, and then pressed with a roll press to obtain a negative electrode / current collector.
However, to the current collector obtained in Preparation Example 5 of the current collector, the negative electrode paste was applied by diluting twice with N-methyl-2-pyrrolidone and dried twice at 130 ° C. for 3 hours. Repeatedly, a negative electrode / current collector was obtained.

Evaluation of Adhesiveness between Electrode and Current Collector Adhesion between the electrode layer and current collector is a cross-cut method test of a 25 square grid pattern (cut interval 2 mm) according to JIS K-5600-5-6. Immediately after and 10C charge / discharge between 4.2 V and 3.0 V (6 minutes for both charging time and discharging time), the adhesion state was evaluated in 6 stages from 0 to 5. The smaller the number, the better the adhesion.

[Production example of storage battery]
The positive electrode and negative electrode material pastes were applied to the current collector obtained in the current collector preparation example, wound through a 25 μm thick polypropylene / polyethylene / polypropylene porous film, and stored in a cylindrical sealed container. A storage battery having a cell voltage of 3.7 volts and a capacity of 1,200 mAh was obtained by impregnating with a solution of molar lithium hexafluorophosphate in ethylene carbonate and methyl ethyl carbonate (volume ratio of 1: 1).

Evaluation of capacity retention rate The storage battery was evaluated by the ratio of the capacity after initial charge of 100 cycles of 20C charge / discharge between 4.2V and 3.0V (both charge time and discharge time is 3 minutes).

Evaluation of internal resistance For the storage batteries produced by the respective methods, the internal resistance after 100 cycles of charging and discharging 10C between charging voltage 4.2V to 3.0V (6 minutes for both charging time and discharging time) was measured. The resistance increase rate after the cycle was evaluated. The measurement method was an alternating current four-terminal method, and was measured at a frequency of 1 kHz and 10 mA.

[Evaluation of fabricated electrodes and storage batteries]
[Example]
Table 1 summarizes the evaluation results of the examples of the electrodes and storage batteries prepared using the current collectors of the above-described Adjustment Examples 1 to 5 obtained by electrodeposition coating.
[Comparative example]
Table 1 shows the evaluation results of comparative examples of electrodes and storage batteries produced using a current collector that was not treated by electrodeposition coating (untreated current collector).

  The current collector for a storage battery of the present invention can be suitably used for a current collector application of a storage battery that requires excellent cycle characteristics with little deterioration during rapid charge / discharge and low resistance.

DESCRIPTION OF SYMBOLS 1 ... Unwinding roll 2 ... Current collector base 3 ... Feeding roll 4 ... Electrodeposition coating tank 5 ... Electrodeposition paint 6 ... Counter electrode with diaphragm 7 ... Recovery tank 8 ... Washing tank 9 ... Drying tank 10 ... Winding roll 11 ... Electrodeposition paint receiving tank 12 ... Electrodeposition paint recovery line 13 ... Pump 14 ... Electrodeposition paint supply line

Claims (7)

  A current collector for a storage battery, wherein a conductive film is formed on a current collector substrate by an electrodeposition coating method.   The current collector for a storage battery according to claim 1, wherein a conductive electrodeposition paint containing a cationic polymer resin or an anionic polymer resin and a carbon particle conductive agent is used.   The current collector for a storage battery according to claim 1 or 2, wherein the current collector base is made of a metal or an alloy, and the thickness of the conductive coating is 0.1 to 15 µm.   The current collector for a storage battery according to claim 2 or 3, wherein the carbon particle conductive agent has a diameter of 3 µm or less.   The current collector for a storage battery according to any one of claims 1 to 4, wherein the current collector base comprises a perforated metal foil or a foam metal.   The manufacturing method of the electrical power collector for storage batteries in any one of Claims 1-5.   A storage battery using a storage battery electrode and a storage battery electrode manufactured by applying a coating liquid containing an electrode active material to the storage battery current collector according to claim 1.

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